The disposable hygiene market desires a highly elastic, breathable, nonwoven fabric with the necessary aesthetic qualities, and preferably fabrics that require no form of mechanical activation, all while being cost effective. Existing products tend to be layered composite structures comprised of an elastic film (typically a styrenic block copolymer (“SBC”)) that has skin layers coextruded or otherwise laminated onto the film to prevent blocking. The skin layers used are typically inelastic, nonwovens in order to provide the correct aesthetic (a soft, fluffy, cushion-like texture). In certain constructions a hot melt glue layer is used to bond the nonwoven to either side of the elastic film, and in other constructions an inelastic film layer is used to create a deadzone for attachment purposes. Once these composite structures are formed they are typically not elastic due to the constraining influence of the inelastic components such as the skin layers, glue, and nonwoven facing layers.
In order to remove the constraining influence, these composites require a mechanical stretching or activation step in order to stretch or break the nonelastic components, removing the constraint and creating an elastic composite controlled by the elastic film. Also, the products require the film to be apertured in order to make these layered structures breathable. This process involves the controlled puncturing/tearing of the film with the associated concerns for film failure and increased scrap rates.
Recently, film composites have arrived in the market that do not require mechanical activation. These products still comprise a SBC film with one or more highly extensible spunlaced facing layers attached to either side of the film using thin lines of hot melt glue. Because the film does not have a coextruded skin, the regions between the glued areas are not constrained and are therefore elastic as the nonwoven is extensible and non-restraining. However, these products are not breathable, require adhesives and like all of the film composite products are costly to produce.
A solution to the above problem is to modify commercially available meltspun lines to produce in-situ a multilayer laminate fabric from a single die. For example, the modification of the meltspinning die could allow for the formation of a three-layer ABA in-situ laminate fabric having high loft, extensible “A” layers made from polymers with a desirable hand that are joined to the “B” layer comprised of a highly elastic propylene-based elastomers. Since they are produced side-by-side simultaneously, the fabric layers would be joined to one another through fiber-fiber entanglement across an interfacial layer between the two fabric layers. This would result in a fabric that is highly elastic, breathable and has the desired aesthetic qualities.
Some related disclosures include EP 1 712 351 A, U.S. Pat. No. 4,380,570, U.S. Pat. No. 5,476,616, U.S. Pat. No. 5,804,286, U.S. Pat. No. 5,921,973, U.S. Pat. No. 6,080,818, U.S. Pat. No. 6,342,565, U.S. Pat. No. 6,417,121, U.S. Pat. No. 6,444,774, U.S. Pat. No. 6,506,698, U.S. Pat. No. 7,026,404, U.S. Pat. No. 7,101,622, US 2003/0125696, US 2005/0106978, US 2006/0172647, U.S. Pat. No. 6,342,565, US 2005/0106978, US 2005/0130544, US 2006/0172647, US 2008/0182116, US 2008/0182940, US 2008/0182468, U.S. Ser. No. 11/655,399, and R. Zhao, “Melt Blowing Polyoxymethylene Copolymer” in INT'L NONWOVENS J., 19-24 (Summer 2005).